Initial rewrite of the file accessors from Perl to C++.

This is especially important for the extremely slow AMF parser.
Also there is a new file handler for the Prusa Control 'PRUS' format.

xs/src/libslic3r/Format/STL.hpp

@@ -0,0 +1,17 @@
+#ifndef slic3r_Format_STL_hpp_
+#define slic3r_Format_STL_hpp_
+
+namespace Slic3r {
+
+class TriangleMesh;
+class ModelObject;
+
+// Load an STL file into a provided model.
+extern bool load_stl(const char *path, Model *model, const char *object_name = nullptr);
+
+extern bool store_stl(const char *path, TriangleMesh *mesh, bool binary);
+extern bool store_stl(const char *path, ModelObject *model_object);
+
+}; // namespace Slic3r
+
+#endif /* slic3r_Format_STL_hpp_ */